METHOD FOR RESIDUE-FREE BLOCK PATTERN TRANSFER ONTO METAL INTERCONNECTS FOR AIR GAP FORMATION

摘要

A selective wet etching process is used, prior to air gap opening formation, to remove a sacrificial nitride layer from over a first region of an interconnect dielectric material containing a plurality of first conductive metal structures utilizing a titanium nitride hard mask portion located over a second region of the interconnect dielectric material as an etch mask. The titanium nitride hard mask portion located over the second region of the interconnect dielectric material is thereafter removed, again prior to air gap opening formation, utilizing another wet etch process. The wet etching processes are used instead of reactive ion etching.

主权项

1. A method of forming an interconnect structure containing air gaps, said method comprising
providing a structure having a plurality of first conductive metal structures located in a first region of an interconnect dielectric material and a plurality of second conductive metal structures located in a second region of said interconnect dielectric material; forming a masking material stack comprising, from bottom to top, a sacrificial nitride layer and a titanium nitride hard mask layer over said structure; removing said titanium nitride hard mask layer from over said first region, but not said second region, of said interconnect dielectric material; removing said sacrificial nitride layer from over said first region of said interconnect dielectric material utilizing a wet etch process, wherein a remaining portion of said titanium nitride hard mask layer located over said second region of said interconnect dielectric material serves as a mask during said wet etch process; removing said remaining portion of said titanium nitride hard mask layer over said second region of said interconnect dielectric material utilizing another wet etch process; providing air gap openings within said first region of said interconnect dielectric material, wherein during said providing said air gap openings a remaining portion of said sacrificial nitride layer is removed from atop said second region of said interconnect dielectric material; and forming a dielectric capping layer over said first region and said second region of said interconnect dielectric material, wherein portions of said dielectric capping layer seal said air gap openings forming air gaps within said first region of said interconnect dielectric material.